Room Construction for a Clean Agent System
Clean Agent Systems are the best fire protection system for your server rooms. For this suppression system to work properly, your server room construction needs to be specifically designed to limit leaks and hold the gaseous agent.
In reports from the NFPA, when automatic extinguishing equipment was reported present, sprinklers were reported in 72% of the fires. Wet-pipe sprinklers were reported for 90% of the fires with sprinklers present, compared to 7% for dry-pipe sprinklers and 3% for other sprinklers.
When wet-pipe sprinklers were present, 56% of fires were reported as too small to activate operational sprinklers. Clean agent systems can activate faster than traditional wet-pipe sprinklers and, since they do not use water, will not damage your electrical equipment when used. Debris, smoke, and water clean-up wreaks havoc on electronic gear. It also prevents your business from getting back to business as usual.
Server Room Construction for a Clean Agent Suppression System
Server rooms are generally constructed with the perimeter walls extending from the true ceiling (as opposed to drop ceilings and the like) to the lowest structural unit, either the floor itself or the concrete slab underneath the floor. This creates a fire rated barrier for the room and reduces the leaks a room will have in an Integrity Fan Test.
Server rooms should be prepared for a clean agent suppression system by inspecting the walls and slab for leakage points, sealing them with fire retardant materials, and fitting the doors with pressure seals around the jams and thresholds.
When constructing a server room, your contractors should ensure the following points are followed to allow for a clean agent suppression system.
Doors & Windows
- All doors must have a threshold and sweep installed
- Egress doors should swing out of the protected space
- Doors may require weather stripping around the jam to ensure an air tight seal
- Latching mechanisms are necessary and door closures are required
- If doors to the server room must remain open, an electromagnet door holder will be required which can be released prior to agent discharge
- All types of windows, pass through, or openings must be fire caulked and sealed
- Porous block walls must be sealed from slab-to-slab to prevent gas from leaking out of the block; two or three coats of paint are typically required
- Server rooms should be enclosed with wall partitions that extend slab-to-slab; in areas where this is not possible, all ceiling tiles should be clipped and openings caulked
- All walls should be caulked around the inside perimeter of the room where the walls rest on the floor slab and the walls intersect with the ceiling slab above
- Upgraded, noncombustible ceiling tiles are recommended
- Drywall should be caulked at the joints of the walls and floor, and at the roof or floor above
- Any penetration to the walls, including conduit, cable trays, outlets, switches and wire troughs, must be fire caulked and sealed
- If a raised floor continues out of the protected space, bulkheads must be installed under the floor directly under the partitions; these bulkheads must be caulked top and bottom
- All floor drains should have traps which are designed to have water in them at all times
- To ensure the protected area is air tight, dampers may be required in the ductwork at the perimeter walls of each protected space
- Dampers must be spring loaded or motor operated to provide 100% air shut off
- A 5% minimum leakage requirement must be met so the dampers must be UL #5555
- With clean agent fire suppression, the HVAC will be shut down prior to discharge, self-contained HVAC units may continue to run (if included in design calculations)
- HVAC shut down control relays should be installed to within 3 feet of each unit
- All exhaust fans should be dampered; fire alarm system control relays are used to shut down any fans
- All fresh air intakes should be dampered and closed using fire alarm system control relays
Power and Interface Wiring
- 120 VAC dedicated 15 AMP circuit to the suppression control panel is required
- Power to all dampers – control relays within 3 feet of damper
- Fire alarm monitoring – contacts for alarm, supervisory and trouble conditions are available within the fire control panel; connection is handled by your fire system contractor
- Purge system control wiring to HVAC units and exhaust fans are interfaced with fire alarm system control panel; connection is handled by your fire system contractor
Pressure Relief Vents
While ensuring that your server room is sufficiently sealed to contain the suppression agent for at least 10 minutes, you also have to take into consideration the maximum amount of pressure the room’s construction can withstand. The suppression agent is released with force, in a sealed room, if not calculated properly the pressure could be higher than the room can withstand. NFPA 2001, Section 5.3.7 states, “if the developed pressures present a threat to the structural strength of the enclosure, venting shall be provided to prevent excessive pressures.” Your suppression system designer should calculate Peak Pressure equations for your server room to determine if you need Pressure Relief Vents installed.
In addition to calculating if a pressure relief vent is necessary, and what size it should be, your designer should also calculate the leakage rate for the vent to ensure it will open and close at the correct pressure and will vent the proper amount of pressure to outdoors.
If Pressure Relief Vents need to be installed, here are some guidelines for optimizing performance:
- Install vents as high as possible so that the lighter air, not the denser agent, is vented
- Vents should open at pressures no lower than .007 PSI (50 Pa) so they don’t open unintentionally under normal HVAC pressures and no higher than .02 PSI (100 Pa) so the pressure is vented early enough to prevent it from becoming excessive
- Specify the correct direction for venting with the Pressure Relief Vent. Inert agent discharges always create positive pressures and must have venting out of the enclosure, but halocarbons may create positive and/or negative pressures creating a need to be vented in either direction or both, depending on the agent and the humidity
- All Pressure Relief Vents should be inspected annually to confirm they will open according to their specifications and to verify that the vent path to outdoors has not been accidently restricted
Posted on: October 25, 2016